This disclosure relates to electrical generators, and more particularly to electrical generators having bearings for supporting the rotor shaft.
In electrical generators, such as those used to power electrical systems of aircraft, the electrical generator is connected to the main engine of the aircraft by a drive shaft. The drive shaft is connected to a rotor assembly of the electrical generator through a rotor shaft. The rotor assembly is mounted on the rotor shaft and rotates within a stator assembly. The rotor shaft is supported for rotation in a generator housing using bearing assemblies.
Previous electrical generators have been manufactured with light weight aluminum or magnesium frames mounted to a housing of the electrical generator. Hardened steel bearing liners are shrunk fit or cast into the aluminum or magnesium frame, which has also been referred to as an end bell, to provide a low-wear surface to mate with a steel bearing outer ring of the bearing assembly. When so fitted, the combined thermal expansion rate of the aluminum or magnesium frame and steel bearing liner is greater than the thermal expansion rate of the steel bearing outer ring. Therefore the liner expands away from the bearing outer ring which increases the clearance between the liner and the bearing outer ring. This can lead to fretting corrosion and reduced bearing system reliability.